Sherpa is, nigh undisputably, one of the best if not the best unit in Berwick saga. At the moment of join, he instantly becomes an incredibly capable combat unit - with his prf, the Primlarga, he can output incredible amounts of damage immediately and since it has A durability, it's unlikely that it'll break if the player makes good use of repair stones. He has an incredible Sword Skill base of 36, meaning he'll never struggle to hit enemies. His bulk, although his defense is middling, is redeemed by his incredibly high HP, and as a result he is almost never at real risk of death.

He also, notably, is the only unit in the game with the Counter skill, which along with allowing him to have guaranteed retaliation on 0 range attackers without the Primlarga or any other + weapon, also allows him to have guaranteed cut through on enemy 1 range attackers. This only occurs, however, if he has higher AS than the enemy attacking - which, obviously, isn't much of a problem because the majority of enemy 1 range attackers are wielding incredibly heavy crossbows. This combines nicely with his high hit rates, and good bulk, allowing him to deliver damage to wide numbers of enemies in a single phase without being at risk of death.

He has a staggeringly low happiness requirement of 1, meaning that you'll only need to buy him and then deploy him in one side mission to meet it. He can then be easily permanent recruited by talking to Kay in Chapter 8. This is, perhaps, his greatest strength: he requires next to no active investment to contribute throughout the entire game, and as a result can be easily put aside to train up other units (which Berwick heavily incentivises) then picked up again when needed and be just as competent as he was at join time.

Overall, Sherpa is an incredible asset to the player, and is always ready on demand.